Effect of Press Fit on Lateral Stem Stresses and the Integrity of Porous-Coated Femoral Prostheses PDF Download
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Author: M. Bushelow Publisher: ISBN: Category : Alloys Languages : en Pages : 12
Book Description
A strain gage analysis was performed to determine the stresses generated on the lateral surface of two types of porous-coated femoral prostheses. One type of prosthesis was made of wrought titanium (Ti-6Al-4V) alloy with a porous polysulfone coating; the other was a porous-coated alloy meeting the requirements of the ASTM Specification for Cast Cobalt-Chromium-Molybdenum Alloy for Surgical Implant Applications (F 75-82). Various degrees of fit were evaluated, ranging from a loose fit to one in which the stem was cemented into the femoral canal. The results showed that modeling pressfit porous-coated stems using cemented conditions can produce peak stresses on the lateral surface of the stem significantly lower than those for noncemented stems. Based on the fatigue strength of the stem material, the authors show that assessing stem integrity with the assumption that the cemented stem represents a complete bone ingrowth condition may lead to a design evaluation of the femoral stem that is overoptimistic for in vivo fatigue load conditions.
Author: M. Bushelow Publisher: ISBN: Category : Alloys Languages : en Pages : 12
Book Description
A strain gage analysis was performed to determine the stresses generated on the lateral surface of two types of porous-coated femoral prostheses. One type of prosthesis was made of wrought titanium (Ti-6Al-4V) alloy with a porous polysulfone coating; the other was a porous-coated alloy meeting the requirements of the ASTM Specification for Cast Cobalt-Chromium-Molybdenum Alloy for Surgical Implant Applications (F 75-82). Various degrees of fit were evaluated, ranging from a loose fit to one in which the stem was cemented into the femoral canal. The results showed that modeling pressfit porous-coated stems using cemented conditions can produce peak stresses on the lateral surface of the stem significantly lower than those for noncemented stems. Based on the fatigue strength of the stem material, the authors show that assessing stem integrity with the assumption that the cemented stem represents a complete bone ingrowth condition may lead to a design evaluation of the femoral stem that is overoptimistic for in vivo fatigue load conditions.
Author: G. Buchhorn Publisher: Seattle ; Toronto : Hogrefe & Huber ISBN: Category : Medical Languages : en Pages : 456
Book Description
A summary of the state-of-the-art on factors decisive for the safety and long-term function of total joint replacements, in papers from the third Biomaterials Symposium, held in 1987 at the U. of Gottingen, Germany. The volume is divided into sections on requirements on implant security; strength of the biomaterials; tribology of various couplings; shape and dimensions; corrosion and degradation; implant anchorage; bone reaction and bioactivity; custom made implants; manufacturing and quality control; instruments and implant retrieval; clinical experiences, carcinogenicity, and other aspects. For clinicians and researchers from many fields interested in joint replacement. Annotation copyright by Book News, Inc., Portland, OR
Author: DS. Hungerford Publisher: ISBN: Category : Alloys Languages : en Pages : 15
Book Description
Strain analysis of human cadaver femora after cemented total hip arthroplasty (THA) has demonstrated a reduction in stress transfer along the proximal femur. The principal objective of this study was to determine the effect of the cementless application of a pressfit, porous-coated prosthesis on the strain experienced by the proximal femur. Using the photoelastic coating technique (PECT), five human cadaver specimens were subjected to strain analysis before and after cementless arthroplasty with a PCA total hip prosthesis. After total hip replacement, the strain magnitudes were reduced for all points along the medial border when the femur was subjected to loading conditions. A reduction of the level of strain experienced by the calcar ranged from 34.7 to 43.7% under loads ranging from 750 to 2000 N--a considerably smaller reduction than that reported by previous investigators. The region of the greater trochanter was the only area of the lateral surface to demonstrate an increase in strain magnitude after THA; the other, more distal points laterally experienced a reduced level of strain. Increases in strain magnitude, although not statistically significant, were detected along the anterior aspect of the femora. Significant decreases in strain were observed at the two more distal points posteriorly, with no significant change proximally. As this investigation is an evaluation only of the immediate effect of the design of the prosthesis in achieving a press fit, and the specimens are without the benefit of bony ingrowth, additional studies are necessary to determine the effect of biologic ingrowth on the distribution of strain within the proximal femur.
Author: NB. Beals Publisher: ISBN: Category : Alloys Languages : en Pages : 15
Book Description
Concerns about the metal ion release, high stiffness, and reduction in stem strength that are associated with porous metal coatings have prompted investigations of a relatively high-strength porous polymeric coating, porous polysulfone (PPSF). The present study was initiated in order to characterize the mechanical properties of PPSF and PPSF-coated titanium alloy and to evaluate the performance of PPSF as a coating on titanium alloy femoral stems in dogs. PPSF with various porosities was fabricated by sintering particles of Union Carbide P-1700 medical-grade polysulfone. Chemical coupling of PPSF to Ti-6Al-4V alloy specimens was achieved using silyl-reactive polysulfone. The shear strength of the PPSF/titanium alloy interface determined from push-out tests on coated cylindrical rods and transverse sections of the coated canine femoral stems was found to exceed 16 MPa. Tension and punch shear tests performed on the PPSF yielded values of 13 and 21 MPa, respectively. The relationship between strength and porosity characteristics was determined. Fatigue tests performed on PPSF-coated titanium femoral stems revealed no failure of the coating up to 1 million cycles. No difference between PPSF-coated and uncoated titanium specimens was found in the fatigue behavior. PPSF-coated titanium alloy canine femoral stems (32% porosity, 246 μm in average pore size) were implanted in 25 dogs. Evidence of loosening was found only in those animals in which the canal/fill ratio was low. No gross radiographic changes were found in the implanted femurs within the two-year postoperative period. Histology showed bone ingrowth fixation of the prostheses. Results of this investigation indicate that PPSF-coated femoral stems warrant continued investigation.
Author: M. Bushelow
Author: M. Bushelow
Author: Jack E. Lemons
Author: 
Author: G. Buchhorn
Author: Cornelis de Putter
Author: DS. Hungerford
Author: 
Author: 
Author: Stephen Girard Desormeaux
Author: NB. Beals